It is increasingly recognized that molecular and cellular imaging approaches are needed to provide a personalized portrait of disease states and to track responses to therapeutic regimens. Currently, the use of visible-light excitable fluorophores is limited due to poor tissue penetration and autofluorescence caused by the excitation light.
The present invention is directed to the downconversion properties of the specifically coated rare earth materials. The current state of the art has been focused exclusively on the upconversion properties of rare earths. Applicants now discovered that certain coated rare earth materials can be specifically tuned to optimize shortwave infrared emissions for the purpose of non-invasive infrared imaging applications. Biomedical infrared imaging (i.e., where both excitation and emission is in the infrared) has not heretofore been utilized by either the rare earth or biomedical imaging communities.